Microelectronic devices such as integrated circuits, for example, are typically combined with a substrate and assembled in a package that is soldered or connected to a printed circuit board prior to use. One method of connecting an integrated circuit to a substrate is known in the art as controlled collapse chip connection (C4) flip chip manufacturing. Flip chip manufacturing includes an integrated circuit having contact pads (e.g., electric terminals) placed on one side of the die so that it can be flipped over and bonded with adhesive with the contact pads providing an electrical connection with contact bumps on a package substrate. Such adhesives are typically filled with fine silica particles in order to compensate for differences in coefficient of thermal expansion (CTE) between flip chip components.
One form of flip chip manufacturing involves wafer level packaging using lead-free solder to form electrical contacts between the integrated circuit and substrate. Wafer level packaging uses an underfill process to fill voids that may otherwise exist between the integrated circuit and the substrate. Voids between the integrated circuit and substrate weaken the structural integrity of the integrated circuit/substrate interface that may lead to delamination during thermal and/or moisture loading. One problem that may arise in a flip chip manufacturing process using lead free type solder is that the chip connection is either not collapsible or only minimally collapsible, thereby forming large voids between the microelectronic device and substrate when packaged.